BARI (ITALY) -Pope Francis on Saturday voiced concern that Christians will disappear from the Middle East amid "murderous indifference," as church leaders from Syria and Lebanon called on Western states to help return Syrian refugees.

The Argentine Pope was addressing the leaders of almost all the Middle Eastern churches gathered in the port city of Bari to pray for peace in the region.

"The Middle East has become a land of people who leave their own lands behind," Francis said.

"There is also the danger that the presence of our brothers and sisters in the faith will disappear, disfiguring the very face of the region.

"Indifference kills, and we desire to lift up our voices in opposition to this murderous indifference."

Lebanese cardinal Bechara Rai, the patriarch of the Maronite Church, said governments should from now on encourage Syrian refugees to return to their country, because "bombings are extremely localised".

States must "financially help people driven from their lands to repair their homes," he said, instead of "repeatedly saying that there is no peace".

More than 350,000 people have been killed since Syria's brutal civil war began in 2011, with millions more displaced.

Lebanon, a country of cultural and religious diversity, has taken in some 1.75 million refugees.

On Saturday, a ceasefire deal in the south between the government and rebels allowed thousands of displaced Syrians to return home. The accord follows a string of similar deals with rebels for other areas of Syria, Syrian Observatory for Human Rights monitoring group said.

- Islamic regime fear -

The Melkite Greek Catholic archbishop of Aleppo Jean-Clement Jeanbart said he has launched a campaign to return Syrians, called "Aleppo is waiting for you" funded by Swiss benefactors.

Of the 170,000 Christians in the city before the war, around 60,000 remain, he said. Those who have sought refuge in neighbouring countries are expected to return, unlike those who have fled to the West.

"Now that security has returned, help us at home," he said, adding that the Syrian regime is "credited with emphasising secularism, diversity and equality for all citizens".

The only alternative is a fundamentalist Islamic regime, he warned.

The Syrian-Orthodox Patriarch Ignatius Ephrem II, who lives in Damascus, echoed that "our greatest fear is to replace a secular regime with probably an Islamic one".

According to the Chaldean bishop of Aleppo, Antoine Audo, half of Syria's 1.5 million Christians have fled the country since the unrest broke out.

Churches have been damaged or destroyed, and large numbers of Christians have been murdered or abducted.

Also attending the ecumenical meeting in southern Italy are the patriarch Bartholomew of Constantinople, the spiritual leader of the eastern orthodox church, and metropolitan Hilarion of the Russian orthodox church which is powerful in Syria.